Le 04/09/2009 10:57, Attila Szegedi a écrit :
> Hi folks,
>
> This small testcase fails in MethodHandles.catchException() on MLVM:
>
> import java.dyn.MethodHandle;
> import java.dyn.MethodHandles;
> import java.dyn.MethodType;
>
> public class TestCatchException
> {
> public static void main(String[] args) throws Throwable
> {
> MethodHandle throwing = findStatic("throwing");
> MethodHandle catching = findStatic("catching");
> MethodHandles.catchException(throwing, MyException.class,
> MethodHandles.dropArguments(catching, 0,
> MyException.class));
> }
>
> private static class MyException extends RuntimeException
> {
> }
>
> private static MethodHandle findStatic(String name)
> {
> return MethodHandles.publicLookup().findStatic(
> TestCatchException.class, name,
> MethodType.make(int.class,
> Object.class));
> }
>
>
> public static int throwing(Object o)
> {
> throw new MyException();
> }
>
> public static int catching(Object o)
> {
> return 0;
> }
> }
>
> Notably, it fails with:
>
> Exception in thread "main" java.dyn.NoAccessException: cannot access:
> *.java.dyn.MethodHandle.invoke(TestCatchException
> $MyException,java.lang.Object)int
> at sun.dyn.MemberName.newNoAccessException(MemberName.java:421)
> at sun.dyn.MemberName.newNoAccessException(MemberName.java:412)
> at sun.dyn.MemberName$Factory.resolveOrFail(MemberName.java:517)
> at java.dyn.MethodHandles$Lookup.findVirtual(MethodHandles.java:267)
> at sun.dyn.Invokers.exactInvoker(Invokers.java:66)
> at java.dyn.MethodHandles.exactInvoker(MethodHandles.java:761)
> at sun.dyn.FromGeneric.computeUnboxingInvoker(FromGeneric.java:137)
> at sun.dyn.FromGeneric.makeInstance(FromGeneric.java:160)
> at sun.dyn.FromGeneric.make(FromGeneric.java:174)
> at sun.dyn.MethodHandleImpl.convertArguments(MethodHandleImpl.java:460)
> at sun.dyn.MethodHandleImpl.makeGuardWithCatch(MethodHandleImpl.java:
> 840)
> at java.dyn.MethodHandles.catchException(MethodHandles.java:1397)
> at TestCatchException.main(TestCatchException.java:12)
>
> However, if I replace "MyException" with an exception on the boot
> classpath, i.e. IllegalArgumentException, then catchException() will
> succeed. Any advice for a workaround?
>
If your signature isn't variant (you know the number of arguments)
and have no primitive type in your signature
(or don't mind the overhead), you can create a static method like that
static void catchException(MethodHandle target, Class<? extends
Throwable> c,
MethodHandle
exceptionHandler, Object o) throws Throwable {
try {
target.<void>invoke(o);
} catch(Throwable t) {
if (c.isInstance(t))
exceptionHandler.<void>invoke(o);
else
throw t;
}
}
Create a mh with lookup.findVirtual() and bound (insertArguments) the
target,
the exception class and the exception handler.
> Attila.
>
Rémi
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